U0301: Softwareinkompatibilität mit dem Motorsteuergerät
Was zu tun ist
Nothing is broken. Two of your car's computers are each working perfectly and running software that was never meant to work together.
That is worth understanding before any money is spent, because there is no part that fixes this — it is a programming job, not a repair.
The most important thing to know: do not let the engine computer be replaced on the strength of this code. It is one of the most expensive parts on the car, it has to be programmed to the vehicle, and it may well be the half that is already correct — the code names two computers that disagree, not one that is broken. A replacement arrives with whatever software the supplier put on it, which is often neither of the versions already in your car, so it can leave you with a second mismatch and a large bill.
Say what has been done to the car recently. A module replaced — especially second-hand — a software update or recall, an interrupted reprogramming, or something retrofitted. One of those is almost always the cause, and knowing which saves the whole diagnosis.
Expect this to need a dealer or a specialist with access to the manufacturer's calibration data. A general garage with a code reader may not be able to resolve it however capable they are, and that is worth establishing before paying for diagnosis rather than after.
Was dieser Code bedeutet
A module is running software that does not belong with the engine control module's. U0300 establishes the family and should be read first; this page adds what changes once a code names the partner rather than reporting a module's own inconsistency.
That is the whole difference and it is worth stating plainly. U0300 says a module has found its own software inconsistent. This code says two specific modules have compared notes and disagree — and it names one of them.
Which produces the trap this page exists to prevent: the named module is not the accused.
A mismatch has two halves and either can be the wrong one. The reporting module may be newly programmed and correct, objecting to an engine module still on an old calibration. Or the engine module may be current and the reporting module left behind. The code cannot tell you which, because from inside the vehicle there is no such thing as the wrong one — only a pair that does not agree.
So "replace the engine control module" is wrong twice over. It is wrong because this is software rather than hardware, and wrong again because the engine module may be the half that is already correct. A replacement arrives carrying whatever calibration the supplier shipped, which may be neither of the two versions already in the vehicle — so the usual outcome of replacing a module here is a second, different mismatch on top of an expensive part.
The right question is not "which module is faulty" but "what is the current released calibration set for this vehicle identification number", and then bringing every module on the affected network to it. That is a dealer or specialist question, and it is answerable in minutes by somebody with access to the manufacturer's data.
Why this particular code appears more than most: the engine module publishes the values everything else consumes — engine speed, load, torque, coolant temperature, throttle position, fuel status. The more partners a module has, the more of them notice when its dialect changes. So breadth here reflects the engine module's role rather than the seriousness of the mismatch, and a long list of complaining modules is not evidence that the engine is in trouble.
Wahrscheinliche Ursachen
Hier anfangen
- Software nur an einem Steuergerät aktualisiert · Fachwerkstatt
- Gebrauchtes Steuergerät auf ein anderes Fahrzeug gesperrt · Fachwerkstatt
- Falsche Konfiguration des Steuergeräts nach dem Tausch · Fachwerkstatt
- Programmierung des Steuergeräts abgebrochen · Fachwerkstatt
Seltener
- Motor umprogrammiert oder Fremdsoftware installiert · Fachwerkstatt
- Softwarekalibrierung veraltet · Fachwerkstatt
Symptome
Beteiligte Bauteile
Information, keine Handlungsanweisung
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Lassen Sie alles, wonach Sie handeln wollen, von einer fachlich geschulten Person anhand der herstellereigenen Vorgehensweise für Ihr Fahrzeug prüfen. Nichts hiervon ersetzt diese Vorgehensweise.
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Was einen Bericht lesenswert macht:
- Das Fahrzeug — Marke, Modell, Baujahr und Motor. Derselbe Fehler verhält sich auf jedem anders.
- Was Sie gemessen haben, nicht nur, was Sie getauscht haben.
- Was es tatsächlich behoben hat — oder dass nichts es behoben hat, was ebenso nützlich ist.
Anmelden oder ein Konto anlegen und eintragen, was Sie gefunden haben — zu U0301.